Earthquake analysis of concrete gravity dams on jointed rock foundations

A two-dimensional numerical model for dynamic analysis of jointed rock foundations is presented. The model, based on the distinct element method, employs an explicit time integration algorithm and allows the representation of non-linear behavior of the rock discontinuities and rock matrix. Fluid flow through the discontinuities is also introduced. Absorbing boundaries and a free-field calculation are used to provide dynamic boundary conditions. The paper describes the basic formulation of the model and its application to the earthquake analysis of concrete gravity dams. The effects of the joint slip and separation on the response and permanent displacements of the structure are discussed. A constitutive model for rock joints involving displacement-weakening behavior is used in a simulation of progressive deterioration of dam stability induced by repeated seismic loading.